Concussions are a known cause of epilepsy, but studies about whether concussions exacerbate epilepsy in those who already have it are less fleshed out.

But I guarantee anyone who is considering drafting Fields spent the 10 seconds it took me to find this article suggesting concussion do exacerbate epilepsy and that minor head trauma that would not effect most people can be very detrimental to those who already have epilepsy... as Fields apparently does.

The conclusion:
“ Although further study is required, this observation suggests that a head injury that would be considered benign in the general population can have serious consequences such as recurrence of seizures and medical intractability in patients with epilepsy.”